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 A199239 Number of n X n 0..2 arrays with values 0..2 introduced in row major order, the number of instances of each value within one of each other, and every element equal to zero or two horizontal or vertical neighbors 0
 1, 2, 6, 440, 29227, 1682457, 2013526831 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Diagonal of A199246 LINKS Table of n, a(n) for n=1..7. EXAMPLE Some solutions for n=4 ..0..1..0..1....0..1..1..2....0..1..0..2....0..1..1..0....0..1..0..1 ..1..2..2..0....2..1..1..0....2..0..2..1....2..1..1..2....1..0..2..0 ..0..2..2..1....0..2..0..2....1..2..1..0....1..0..2..0....0..2..0..2 ..2..1..0..2....2..1..2..0....2..0..2..1....0..2..0..2....2..1..2..1 CROSSREFS Sequence in context: A252741 A069261 A053608 * A123261 A124061 A354516 Adjacent sequences: A199236 A199237 A199238 * A199240 A199241 A199242 KEYWORD nonn AUTHOR R. H. Hardin Nov 04 2011 STATUS approved

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Last modified September 29 23:11 EDT 2023. Contains 365781 sequences. (Running on oeis4.)